Devices are known in the prior art to fold and interlock foldable sections of a flat carton blank to form an erected carton suitable as a container for numerous materials. One broad class of carton erecting machines are of the vertical die and plunger type. In general, a reciprocable plunger moving through an "up and down" cycle in a vertical plane forces a flat carton blank through a forming die open at both top and bottom. The sides of the die, whether stationary or movable in whole or in part, fold the side and end panels of the blank around the moving plunger as the plunger passes downwardly through the die, thereby erecting the side and end panels in relationship to the bottom of the box.
Today, where usable for the ultimate containing function, a glueless, interlocking carton will be preferred. Foldable corner lock flaps, each having a tab insertable into a cooperating slit located in an adjacent erected panel, are folded by the cooperating die and plunger, with the last erecting function of the apparatus usually being the locking of the "tab" into its cooperating slit. This is usually accomplished by movable parts on the die and/or plunger which push or pull the tab through the insertion slot. With erection complete, the carton is stripped off the plunger as it changes direction and passes upwardly, back through the die. The carton will then be forwarded to the next step in an integrated packaging operation.
In order to be able to erect carton blanks rapidly and repeatedly in an accurate fashion, an auxiliary carton blank reservoir means is provided to cooperate with a carton blank feeder. The reservoir, or hopper, and feeder apparatus must precisely place each carton blank, one at a time, onto the top of the die. Blank alignment, if not accomplished within narrow limits, will result in imperfect erection; that is, side and/or end panels will not be folded along the preset fold lines and/or locking tabs will not be positioned correctly to slip through the cooperating slits.
To enable the feeding mechanism to directly pull the carton blank onto the top of the die in proper registration for carton erection, the blank reservoir or hopper means must be able to sequentially present carton blanks in proper position for placement on the die without the need for additional blank registration.
Therefore, it is an object of this invention to provide an improved vertical carton erector.
More particularly it is an object of this invention to provide a vertical carton erector including an improved reservoir or hopper.
It is still another object of this invention to provide a vertical carton erector of the die and plunger type capable of rapid and reproducible erections of cartons of the glueless, corner interlocking type.
Another object of the invention is to accomplish the above using the most direct feeding procedure possible, said feeding procedure and accompanying apparatus including supply hopper allowing unusual precision alignment of the carton blank on the forming die without the aid of guide or carton positioning pins on the upper surface of the die.
Other objects of the invention, such as insuring constant pressure advancement of the carton blanks, insuring sequential presentment of carton blanks from the supply hopper at a substantially constant uniform low pressure and to provide these objectives in a supply hopper characterized by a minimum of moving parts, will be apparent to those skilled in the art upon reading the detailed description of the invention hereinbelow in relationship to the drawing.